Disclosed in JP2008-6855A is an example of a known grille control mechanism for a vehicle. According to the grille control mechanism for the vehicle disclosed in JP2008-6855A, a movable member is provided between a front grille and a radiator of the vehicle, so that an aerodynamic characteristic of the vehicle, an engine temperature and the like is adjusted by adjusting inflow of air from a front portion of the vehicle to the radiator, in order to achieve a preferable driving performance of the vehicle. More specifically, the movable member is configured as a movable fin, which is pivotable about a horizontal axis. Accordingly, the inflow of the air is adjusted by controlling an air inlet passage to be opened and closed by the movable fin so that air resistance, lift force or downforce is applied to the vehicle in order to ensure a stable driving performance of the vehicle.
Disclosed in JPH5-50861A is another example of a known grille control mechanism for a vehicle. According to the grille control mechanism for the vehicle disclosed in JPH5-50861A, a movable member (a movable grille) is controlled to be opened and closed in response to an environmental condition (e.g. ambient temperature and the like) and an engine load condition (e.g. a temperature of an engine cooling medium and the like). The grille control mechanism for the vehicle disclosed in JPH5-50861A estimates an opening-closing state of the movable member, by which an appropriate cooling effect is supposed to be obtained under a certain environmental condition and the engine load condition, on the basis of plural determination conditions, which are stored within a storing means. Then, the grille control mechanism executes an opening-closing control of the movable member on the basis of the estimation result in order to adjust cooling of the engine cooling medium to be appropriate.
Both of the grille control mechanism disclosed in JP2008-6855A and the grille control mechanism disclosed in JPH5-50861A are intended to improve the cooling of the engine cooling medium, to achieve a driving stability of the vehicle and the like by controlling the movable member to be at the opened position or the closed position on the basis of each condition. Therefore, in a case where the movable member is displaced from a proper position, where the movable member should be, because of window pressure, an impact and the like applied to the movable member while moving, the engine cooling medium may not be sufficiently cooled or a driving stability of the vehicle may deteriorate.
In other words, in a case where the movable member is closed independently of the control even if the grille control mechanism controls the movable position to be at the opened position in order to cool the cooling medium by inletting the air into the radiator, overheating may occur at the engine because the cooling medium is not sufficiently and appropriately cooled down. Furthermore, in a case where the movable member is opened independently of the control even if the movable member is controlled to be at the closed position so that the downforce is generated at the vehicle in order to obtain the driving stability of the vehicle, the expected driving stability may not be obtained.
A need thus exists to provide a grille control mechanism for a vehicle which is not susceptible to the drawback mentioned above.